Impact tool



Nov. 25, 1941. w. SINKKO 2,263,595

IMPACT TOOL Filed June 9, 1939 INVENTOR Imam Jink/tu Patented Nov. 25; 1941 Waino Sinkko, Bronx, N. Y., assignor to Frederick G. Clover, Denville, N, J.

, Application June 9, 1939, Serial No. 278,287

18 Claims.

This invention relates to impact tools such as scaling hammers and the like and has for its object to reduce vibrations heretofore inherent in such tools, and make operation of such tools less tiring.

One such tool on the market has possessed so much vibration that it is extremely hard on a workman operating the same. Investigation and study has led to the belief these excessive vibrations are due to two causes. One is a pivotal hammer arm causing the motor and handle to be vibrated oppositely to the tool about the pivot of such arm. Another cause is thought to have been the continual contact between the tool and its actuating cam, whereby shocks of impact are transmitted to and through the motor shaft. casing and handle.

According to this invention a tool has been provided which is free of the foregoing disadvantages. The pivotal lever has been eliminated and impact is imparted to the tool by a flying weight or inertia member, which engages the tool only after it has become disengaged from the actuating cam or other driving means. A suitable spring absorbs the shock when the tool is held out of contact with the work. When held in contact with the work, the harder the tool is pressed against the work, the'harder is the blow that is struck.

Referring to the drawing, Fig. 1 is a view partly in section of one embodiment of this invention adapted for attachment to an existing motor driven drill.

pact tool is to be driven, the additional tool or tools may be carried by the motor casing H with the aid of the screw threads 20, and a recessed member 2|, which is adapted to fit over the nut It for driving the cams 22 and 23 on a shaft within the housing or casing of the additional attachment. The threads for the nut l6 are arranged so that the torque due to the driven recessed member 2| tends to tighten the nut it. An anti-friction'or other appropriate bearing 24 is provided between the cams 22 and 23. Weights or inertia members 25 and 26, similar to the inertia member H, are arranged to be engaged by their respective cams as shown. The three-cams, I5, 22 and 23, are preferably angularly displaced about 60 degrees when they are of the shape indicated in Fig. 2, each cam being similar in shape, but angularly displaced from its adjacent cam or cams.

Impact tools 2'! and 28 are engaged by the inertia members 25 and 26 respectively. Asshown v in Fig. 2 the cam casing is provided with threads 29 by means of which a lower guide casing is provided for the flying weight or inertia member in each case. Each flying weight has a light Fig. 2 is a longitudinal section through the rightmost tool casing of Fig. 1.

The driving "shaft I0 is tapered the same amount as are ordinary drill shanks, such as a #1 Morse taper, and is adapted to fit within the tapered drill receiving socket of an ordinary motor driven drill, the smaller end of said shaft being flattened as indicated and as is customary for drills. Surrounding the shaft II] is a casing ll, having in the lower portion thereof a longitudinal slit l2, which is held clamped around the forwardportion of the motor or drill casing.

shoulder on the inertia member. Each spring 30 is just strong enough to raise the weight or inertia member at, 25, or H, into engagement with its cam. Surrounding the impact tool, in each instance is a much stronger coil spring 31, cooperating with the lower part of its enclosing casing and tapered or cone shaped at the top sufficiently to engage the flange 32 on the tool. The purpose of the light spring 30 is primarily to raise the inertia member into contact with the cam, On the other hand, the purpose of the spring 31 is to prevent the tool 28 from falling out and to absorb shocks from the weight 0! inertia member so that when the 'tool is not in contact with the work the spring 3| will, in each instance, absorb substantially all of the shock of impact. The guide casing for the inertia member is preferably in two parts, 33 and 34 for purposes of assembly and is held together by the screw threads 29. Below the portion of the easing 34 is another casing portion 35, necessary for assembling the tool 28 and spring 3|, and is threaded onto the casing portion 34 by the screw threads 36.

A feature of this invention lies in operating the tool at a high enough speed so that the cam gives the inertia member or weight sufficient energy to have it fly out of contact with the cam, and have it engage the impact tool ,only when the inertia member is free from engagement with the cam. The flange 32 engages the under side of the bottom of casing portion 34 to limit upward travel of the impact tool 28 and to permit engagement with the spring 3|. As shown in Fig. 2, the inertia member 26 is still in contact with the cam 23, but is just preparing to move out of contact with the cam compressing spring 30 and engaging the top of the impact tool. 28. The inertia member 26 compresses the spring 3| and moves the impact tool downwardly, Preferably the spring 3| is strong enough to absorb the shock of impact before its convolutions become contiguous one to another. In this way the spring 3| and the flange 32 function to limit movement of the impact tool in each direction. At high speed the thrusts upon the tool 28 will be so frequent that the work engaging end of the tool will appear to be and will be further out of the casing because the spring 3| will be compressed to a substantial extent and for a considerable part of the time. If now the scaling hammer or other impact tool be pressed firmly against the work, the result of that action is to impart stronger blows to the tool 28. The reason for this is that pressing the tool hard against the work shortens its stroke, lessens the amount of thrust to be absorbed by the spring 3 I, and transferring that energy to the tool.

In practice, the flying weight or inertia member has a travel of about "A; of an inch. The upper end portion 31 of the tool is preferably either hexagonal or square in cross-section to prevent turning the tool 28 with respect to the casing 34. In some types of tool such as a star drill, where the tool should turn, the portion 31 should be round and in a hole of polygonal cross-section in the base of the casing 34 so that a nonrotatable tool with a portion 31 of polygonal cross-section may be used. The motor for driving the shaft I is preferably either an electric motor or a compressed air rotary motor. The shaft H) has a normal speed of about twelve to eighteen hundred revolutions per minute.

The higher the speed, the stronger is the blow exerted by the impact tool. With a cam of the type shown in Fig. 2 the flying weight 26 is just ready to leave the contact with the cam 23. After the shaft ID has rotated 90 degrees more or less and usually slightly more, the inertia member 26 is again returned to the cam by the spring 30 so that there are two impacts or blows on each tool for every revolution of the shaft l0. After engagement between the inertia member 26 and the tool 28, the spring 3| assists in returning the weight 26 toward the cam, but due to its flange 32 the actual engagement of the cam and weight occurs only under influence of the light spring 30. The outer surface of the lower casing portion 35 is preferably knurled or otherwise roughened at 38 to facilitate removal of the tool and substitution of another. The cap l9 engages the threads 39 and enables the cams to be operated in a light grease or other appropriate lubricant.

The impact upon the tool in each case occurs only after the flying weight has been disconnected from its actuating cam. The spring 3| in each instance absorbs substantially all the shock upon the impact tool and preferably the spring is strong enough so that such absorption is complete before the spring convolutionstouch one another. The inertia member 26 is in contact with the cam during less than 90 degrees of shaft displacement for each impact upon the tool, so that the weight 26 engages the cam for substantially less than degrees of the shaft rotation at about 1800 R. P. M. The driving motor is preferably of variable speed though such is not needed. The blows struck by the hammer or impact tool are made stronger by either increasing the speed at the driving shaft H1 or by shortening the travel of the impact tool, such as by pressing it hard against the work.

The principal advantage of this invention over the prior practical art is its greater freedom from vibration and shock which means that the tool is easier to work and less tiring upon the workman. In some locations such as in submarine, or subsurface operations in water, the pneumatic motor will be found preferable to the electric motor. So far as this invention is concerned, however, any suitable high-speed motor should be satisfactory.

The weight on its return engages the cam when said cam is not far from the dotted line position for the cam in Fig. 2 which is about 60 degrees or more displaced in a counter-clockwise direction from the full line position shown for the cam. It will be understood the cam in Fig. 2 rotates in a clockwise direction.

Experience has shown there is more vibration present when the tool is off the work than when on, possibly due to the spring 3| having to absorb less energy when the work does so than when the work does not. The spring 30 is desirable to regulate the return of the weight and insure the constancy and regularity of the weigh operation.

I claim:

1. A combination with an impact tool, of a rotary mechanism for actuating the tool, a weight moved toward and from said tool by said mech anism for imparting movement to the tool, said tool and actuating mechanism limiting travel of said weight, means for limiting travel of said tool toward said weight, said tool,,weight and actuating mechanism being so spaced that impact of the weight upon said tool may occur only after the weight has been moved out of contact with said actuating mechanism, and yieldable means for absorbing at least the major portion of the energy of the impact of said weight upon said tool when the tool is out of contact with the work.

2. A combination with an impact tool, of yieldable means cooperating with said tool for absorbing the impact imparted thereto, an inertia member for actuating said tool, other means for moving said inertia member away from said tool, means for imparting a strong enough thrust to said inertia member while out of contact with said tool to enable the member to contact the tool only when out of contact with said thrust imparting means.

3. In an impact device an actuating cam, an inertia member driven thereby away from said cam, a guide for said member, a spring for facilitating the return of said member to said cam, said cam moving fast enough to throw said member out of contact and against said spring, and additional yieldable means on said device for absorbing a larger portion of the energy of impact than said spring absorbs and effective only after the same is out of contact with said cam, said inertia member receiving an axial thrust from said cam.

4. The combination with an impact tool, of a holder therefor, a spring between said holder and tool and strong enough to substantially abmeans and with said inertia member. both, said resilient means being helical springs and the first mentioned resilient means being substantially stiii'er than the second mentioned resilient means, the converting means including a rotatable cam.

9. An impact tool comprising rotary cam actuating mechanism, a casing around said cam, an

, extension from said casing and constituting a for the member to disengage itself from said cam and impinge upon the tool only when out of contact with said cam.

5. The combination with a motor actuated tapered drill receiving holder having a stationary casing, 01 an impact tool attachment adapted to be used in place of a drill and comprising a tapered shaft for reception in said holder, a cam on said shaft, a casing having a bearing for said shaft, said casing having a tubular split part around the tapered portion of said shaft and adapted to be clamped over the tubular part of the casing oi said holder, a guide arranged substantially normal to said tubular portion of the casing, and reciprocating means driven by said camand located in said guide.

6. An impact tool including a rotary motor, means for changing rotary motion into reciprocating motion, a vibratory tool, an inertia member for engaging said tool only when the same guideway for an inertia member engaged and disengaged by said cam, said inertia member being substantially entirely enclosed by said guideway, an internal flange adjacent the end is out of contact with said means, means for yieldably absorbing a large part of the energy oi impact of said inertia member upon said tool, and a casing enclosing an end portion of said tool, said impact absorbing means being adapted to hold said tool within said casing against the same ever falling out.

7. An impact tool comprising means ror converting rotary into reciprocating motion, a reciprocating inertia member engaging and'disengaging said converting means when at its operating speed, means for guiding movements 01 said inertia member, a casing portion removably secured to said guiding means remote from said converting means and retaining an impact tool adapted for engagement and disengagement with said inertia member while the inertia member is disengaged from said converting means, resilient means cooperating with said casing portion and with an abutment carried by the impact tool for moving the impact tool toward the inertia member whereby said resilient means is adapted to absorb a large portion of the energy of impact when the tool is not pressed against work being operated upon.

8. Animpact tool comprising means for converting rotary into reciprocating motion, a reciprocating inertia member engaging and disengaging said converting means when rotated at its operating speed, means for guiding movements of said inertia member, a casing portion.

removably secured to said guiding means remote from said converting means and retaining an impact tool adapted for engagement and disengagement with said inertia member while the inertia member is disengaged from said converting means, resilient means cooperating with said cas ing portion and with an-abutrnent carried by the of the guideway remote from said cam mechanism, a tool extending through and beyond said flange, a buffer spring cooperating with said tool and, an extension on said guideway and biasing said tool toward said inertia member, another spring much lighter than the first, cooperating with said internal flange and inertia member for facilitating the return movement of the inertia member from said tool and into contact with said cam mechanism.

10. An impact tool comprising a rotary actuating mechanism, an inertia member directly actuated thereby, in a direction away from the mechanism, a spring capable of absorbing a large part of the energy of the inertia member, a tool engaged by the inertia member only after its disengagement from said mechanism, said spring cooperating with said tool to urge it toward said member, a stop for limiting recoil of said tool and spring, said member being released from contact with said tool and spring before its contact with said mechanism, said spring being compressed by said member only after contact between member and tool.

ii. Animpact tool comprising, a plurality of edged tools arranged with their edges'in alignment, a holding casing and drive shaft common to said tools, an inertia member for actuating irom its tool, and a shock absorbing spring cooperating with each inertia member only after the member has engaged its tool for taking up most of the energy of the inertia member when its tool is not in contact with the work.

12. An impact tool comprising a rotary actuating mechanism, an inertia member cooperating therewith, a guide casing for directing the movement of said member, an internal flange remote from said mechanism and on said casing, a light spring cooperating with said flange and member for urging the member into engagement with said mechanism, an extension casing removably attached to said guide casing at its end remote from said mechanism, a tool carried by said extension'casing and extending past said flange, an abutment carried by said tool for engagement with said flange to limit the travel or said tool toward said member, a shock absorbing spring cooperating with said tool and extension casing for urging said abutment into contact with said flange, an axial opening in the plane of said flange of polygonal cross-section so that the portion of the tool extending past said flange may be of a cross-sectional shape similar to that of the opening to prevent rotation of the tool, or another extension casing may be attached in place of the aforementioned extension casing and carrying a tool portion of circular cross-section extending past said flange whereby the tool carried by said second extension casing may be rotatable.

13. An impact tool comprising a rotary actuating mechanism, an inertia member engaged thereby, a tool operated by said member only after the member has been disengaged from said mechanism, a shock absorbing spring cooperating with said tool and urging it toward said member, a stop for limiting inward movement oi. said tool under infiuence of said spring, a second spring, lighter than the first, for engagement with said member to facilitate the return of the same into cooperation with said mechanism after the member has been disengaged from said tool and first spring, the first spring being capable of absorbing all the energy of impact of said member on the tool and means for actuating said mechanism, member, and tool at a high enough speed so that the tool may vibrate rapidly and its outward limit of travel be continually reached with substantially no power left in the tool after it has been absorbed by the first spring, or the tool may be pressed against the work to shorten the stroke of the tool and increase the residual energy in the tool so that the strength of blows applied to the work may be generally in proportion to the pressure of the tool against the work.

14. The combination with an impact tool, of a rotary mechanism for actuating said tool, a weight moved toward and from'the said tool by said mechanism for imparting movement to the tool, a stationary guide means for said weight, said tool and actuating mechanism limiting travel of the weight in each direction, said tool, weight and actuating mechanism being so spaced that impact of the weight upon the tool occurs only after the weight has been moved out of contact with said actuating mechanism, and yieldable means for absorbing a large part of a rotary mechanism for actuating said tool, a weight moved toward and from the said tool by said mechanism for imparting movement to the tool, a stationary guide means for said weight, said tool and actuating mechanism limiting travel of the weight in each direction, said tool, weight and actuating mechanism being so spaced that .impact of the weight upon the tool occurs only after the weight has been moved out of contact with said actuating mechanism, and yieldable means for absorbing a large part of the energy of impact of the weight upon said tool when said tool is out of contact with any work, a housing for said tool, an abutment for limiting travel of the tool toward said work, said yieldable means being a spring cooperating with said housing and tool for urging the tool toward said weight.

17. The combination with an impact tool, of a cam, a shaft on which the cam is mounted, a rotary driving mechanism for said shaft, a reciprocating weight actuated by said shaft, a guide for aid weight, said weight engaging said tool only after its release by said cam, a shock absorbing spring cooperating with said tool, a lighter spring cooperating with said weight for Y facilitating the return of said weight to said the energy of impact of the weight upon said' tool when said tool is out of contact with any work.

15. The combination with an impact tool, of a rotary mechanism for actuating said tool, a weight moved toward and from the said tool by said mechanism for imparting movement to the tool, a stationary guide means for said weight, said tool and actuating mechanism limiting travel of the weight in each direction, said tool, weight and actuating mechanism being so spaced that impact of the weight upon the tool occurs only after the weight has been moved out of contact with said actuating mechanism, and yieldable means for absorbing a large part of the energy of impact of the weight upon said tool when said tool is out of contact with any work, and effective only after such impact.

16. The combination with an impact tool, of

cam, said weight engaging said cam only after its disengagement from said tool, the end portion of the weight adjacent the cam being somewhat dome shaped and said cam engaging said weight when a longitudinal axi of the cam is less than degrees with respect to the longitudinal axis of th weight whereby the return of said weight to the cam is somewhat cushioned by a slight wedging action between the weight, cam, and guide, said cam being shaped to eii'ect an increase in velocity of the weight with substantial angular displacement of the cam.

18. A high-speed impact tool comprising a rotary mechanism and shaft, a cam on said shaft, a guide housing, a weight slidable in said housing and substantially axially actuated by said cam, an impact tool engaged by said weight,'and a shock absorbing spring within said housing cooperating with said tool and housing for absorbing substantially all the energy of impact of the.

weight on the tool when the tool is out of contact with its work and for returning the tool into the housing toward the weight, the actuation of said tool being sufficiently rapid to allow the tool to be thrust against the work substantially continuously during a number of strokes of the" tool, the harder the tool is pressed against the work the shorter the stroke of said tool, the less the part of the impact energy of the weight is absorbed by the spring and the greater the part A of such energy is delivered to the-work and the harder the blows of the tool upon the work.

WAINO SINKKO. 

